Firmware upgrading both banks always necessary?

I read somewhere that its necessary to upgrade both banks on the APs due to the GPS firmware? But is it necessary on the SM side?

For ePMP 1000 GPS and 2000, if a GPS update is needed, the radio UI will notify you of this when updating to the most recent firmware.

Regardless of whether or not the GPS needs to be updated, neither AP or SM’s require both banks to be updated with the same firmware revision.